Bleach-containing compositions for bleaching various surfaces, such as fabrics for example, are well known in the art. Amongst the different bleaching compositions available, those relying on bleaching by hypohalite bleach, such as hypochlorite, are often preferred, mainly for bleaching performance reasons. However, such hypohalite bleach composition often faced stability problems. Thus an objective of bleach manufacturers has always been to obtain a bleach product that is chemically and physically stable over time, for example, over periods of storage.
In addition, it is often desirable to add further ingredients, such as dyes or pigments, to hypohalite bleach-containing compositions in order to improve the aesthetics of such compositions. Indeed, coloured bleaching compositions are particularly preferred compositions. As a matter of fact, the distinct appearance of the composition facilitates it's recognition by consumers, thereby reducing potential misuse or consumption of a potentially irritant composition.
However, formulating such coloured bleaching composition has been a constant challenge due to the aggressive nature of hypohalite bleaches. Such formulations often results in variety of stability related problems.
A drawback associated with coloured hypohalite bleach-containing compositions is that pigments and/or dyes, present herein, are decomposed by the bleach. Indeed, hypohalite bleaches are oxidising agents and pigments and dyes are very prone to attacks. In some cases such compounds can even be completely decomposed by such oxidising agents.
This decomposition results, therefore, in the loss of color of the composition and, even, sometimes, in the settling of pigments to the bottom of containers containing such composition. Moreover, as a consequence of the interaction of such components with the oxidising agent, a premature decomposition of the oxidising agent and of other actives present in the composition occurs, leading to a less efficient composition in term of cleaning performances for example. In addition, during oxidation, dyes and/or pigments release ions which attack oxidising agents, resulting thus in the acceleration of the decomposition of such agents.
It is thus an object of the present invention to provide a hypohalite-containing composition, comprising a pigment and/or a dye, in which the pigment is chemically stable and wherein the cleaning performances of the composition are maintained.
It is known in the art to add a stabilising agent to hypohalite bleach-containing compositions in order to prevent, or at least reduce, the decomposition of further ingredients, in particular pigments and/or dye, present in such compositions.
For example, EP-A-0 668 345 and EP-A-1 001 010 relates to bleaching compositions comprising a hypohalite bleach and a radical scavenger. However, even though such stabilization systems, and especially radical scavengers, are capable of stabilising further ingredients, it has been found that pigments and/or dyes are still particularly prone to attacks by hypohalite bleaches and hence are extremely difficult to be stably incorporated into bleaching compositions comprising the known stabilization systems.
Thus, although the systems described in the art provide stabilisation of further ingredients in hypohalite bleach-containing compositions, it has been found that the stabilization of pigments and/or dyes and of the composition may still be further improved.
It is therefore an objective of the present invention to provide hypohalite bleach-containing compositions having excellent bleaching performances and comprising pigments and/or dyes, wherein the decomposition of said ingredients is significantly reduced.
It has now been found that this objective can be met by a hypohalite liquid bleaching composition comprising a pigment and/or a dye, a trimethoxy benzoic acid or a salt thereof, and an alkali metal salt of silicate, an alkali metal periodate or mixture thereof.
Advantageously, the bleaching composition as described herein provides a significant reduction of the decomposition of pigments and/or dyes upon storage of said bleaching composition. Another advantage of the bleaching compositions according to the present invention is that they show excellent bleaching performances. Indeed, the oxidizing agent is not decomposed upon storage of said composition. In particular, the compositions of the present invention provide excellent bleaching performance when used in any laundry application (“fabric treatment applications”), e.g., as a laundry detergent, a laundry additive and/or a laundry pretreater.
A further advantage of the compositions of the present invention is that they are suitable for the cleaning of different types of fabrics including natural fabrics (e.g., fabrics made of cotton, viscose, linen, silk and wool), synthetic fabrics such as those made of polymeric fibers of synthetic origin as well as those made of both natural and synthetic fibers.
Yet another advantage of the bleaching compositions of the present invention is that said bleaching compositions are also suitable for the bleaching of different types of surfaces including hard-surfaces like floors, walls, tiles, glass, kitchen surfaces, bathrooms surfaces, toilet bowls and/or dishes and the like, in addition to the above mentioned fabric treatment applications.